Phthalic acid calculations

Potassium hydrogen phthalate, KHP, is a salt of the intermediate form of phthalic acid. Calculate the pH of both 0.10 M and 0.010 M KHR... 

Table 3 presents the experimental enthalpies of formation of polynitrobenzenes and Table 4 presents the calculated additivity values and DSEs for these same compounds. Enthalpy-of-formation values have been determined experimentally for all three dinitrobenzene isomers in the gaseous state. The enthalpy-of-formation difference between the meta and para isomers is indistinguishable from 0. Conventional wisdom suggests that the para isomer should be destabilized relative to the meta because of adjacent positive charges in key ionic or polar resonance structures. Thus it seems that electronic effects due to meta/para dinitro substituent position are small. This small enthalpy-of-formation difference is similar to that for the meta and para dicyano, difluoro and dichloro benzenes, but does not mimic the ca 22 kJ mol 1 difference for the phthalic acids with which the... 

The phthalocyanines, naphthalocyanines, and certain of their metal derivatives (Figure 6.17) are infrared fluorophores. 61"64 As a class, they are exceptionally stable compounds, with copper (Cu) phthalocyanine (not a fluorophore) remaining intact above 300 °C in air. First used for textile dyeing in the last century and still widely used, there is a rich chemistry of phthalocyanines. Most derivatives can be made by prolonged heating of a phthalimide or phthalic acid derivative with a metal in powder or salt form at elevated temperature. Several derivatives absorb in the near-IR, and either fluoresce or phosphoresce. The electronic transitions of phthalocyanines are complex and have been extensively studied, at least in part because the symmetry of the molecule makes theoretical calculations of its spectroscopic behavior more tractable. Unsubstituted phthalocyanines and naphthalocyanines are, as a class, very insoluble in solvents other than, for instance, nitrobenzene. Sulfonated phthalocyanines are water soluble and exhibit spectra comparable to the parent derivative. Photolumines-cent phthalocyanines (Pcs) include SiPc, ZnPc, and PC itself. These compounds have been little used for practical infrared fluorometry to date however, Diatron Corpora-... 

Smdies of the thermal degradation of several aromatic acids have been reported. Phthalic acid (80), but not isophthalic acid (81) or terephthalic acid (82), decomposes via dehydration to its anhydride at 140-160 °C. However, (81) and (82) and benzoic acid are thermally stable below 200 °C. Dissociation constants of all 19 isomers of methyl-substimted benzoic acids (83) have been measured in methanol and DMSO. From the pA a values, the substiment effects of the methyl groups were calculated and tentatively divided into polar and steric effects. Also, in the case... 

The average functionality of nonstoichiometric mixtures has been deduced [Pinner, 1956] as being equal to twice the total number of functional groups that are not in excess divided by the total number of all molecules present. This simply takes into account the fact that the extent of polymerization (and crosslinking, if it can occur) depends on the deficient reactant. The excess of the other reactant is not useful in fact, it results in a lowering of the functionality of the system. For the above nonstoichiometric mixture of 1 mol of glycerol and 5 mol of phthalic acid, the /avg value is correctly calculated as 6/6 or 1.00. This low value of /avg is indicative of the low degree of polymerization that will occur in the system. 

In many reaction systems the difference between the observed pc values and those calculated from Eq. 2-148 are at least partially ascribed to the failure of the assumption of equal reactivity of all functional groups of the same type. An example is the glycerol-phthalic acid system previously mentioned. The difference between the calculated and observed values of pc (0.709 vs. 0.765) would be decreased, but not eliminated, if the calculation were corrected for the known lower reactivity of the secondary hydroxyl group of glycerol. 

G. Calculate the voltage of the following cell, in which KHP is potassium hydrogen phthalate, the monopotassium salt of phthalic acid. 

Values of rate constants in reaction (18 a) have been calculated (40) by means of this and similar treatments for a-ketoacids (44, 45), pyri-dinecarboxylic acids (46, 47), unsaturated acids (48, 49), phthalic acid (50), carbonyl compounds (51,52), iodobenzenes bearing ionisable groupings (53), etc. 

Intermediates and Products of Side Reactions under Colors, Appendix IIIC, using the following Sample Solution Transfer 2 g of sample, accurately weighed, into a 100-mL volumetric flask dissolve in and dilute to volume with water. Calculate the concentrations of 2-(2,4-dihydroxy-3,5-diiodobenzoyl) benzoic acid, iodine, phthalic acid, sodium iodide, and triio-doresorcinol, using the following absorptivities ... 

If 0.0100 mol of phthalic acid is dissolved per liter of water, calculate the equilibrium concentrations of H2Ph, HPh, Ph ,and H3O+. 

If a solution is prepared in which the initial concentration of MnCl2 is 5 X 10" M and that of phthalic acid is 5 X 10 Af, and the pH is then adjusted to 7, calculate the fraction of soluble Mn that is complexed with the organic acid at equilibrium. (Ignore activity corrections, which are small in this solution of low ionic strength.)... 

Calculate, for a 10-g sample of soil organic matter suspended in a liter of 10" M MnCb, the fraction of Mn " complexed in the pH range of 4 to 9, using first acetic and then phthalic acid to model the actual functional groups of the organic matter. (The carboxylic acid content of the organic matter can be taken to be 800 mmoles/kg.)... 

Equation (5.123) can be used to calculate the extent of reaction required to reach the onset of gelation in a mixture of reacting monomers from its average functionality. Thus, for a glycerol-phthalic acid (2 3 molar ratio) stoichiometric system,... 

The alkaline hydrolysis of phthalate diesters has been fit to the Taft-Pavelich equation (Eq. 9). Dimethyl phthalate (DMP) hydrolyzes to phthalic acid (PA) in two steps DMP + H20->MMP + CH30H and MMP + H20- PA + CH30H. The first step is about 12 times faster than the second, and nearly all the diester is converted to the monoester before product PA is formed. Other diesters are assumed to behave similarly. An LFER was obtained from rate measurements on five phthalate esters (Wolfe et al., 1980b). The reaction constants, p and S, were determined by multiple regression analysis of the measured rate constants and reported values of cr and Es for the alkyl substituents. The fitted intercept compares favorably with the measured rate constant (log kOH = — 1.16 0.02) for the dimethyl ester (for which a and s = 0 by definition). Calculated half-lives under pseudo-first-order conditions (pH 8.0, 30°C) range from about 4 months for DMP to over 100 years for di-2-ethylhexyl phthalate. 

Calculate the concentration of CSH4O4 (a) in a 0.010 M solution of H2CgH404, (b) in a solution which is 0.010 M with respect to H2C8H4O4 and 0.020 M with respect to HCl. The ionization constants for H2C8H4O4, phthalic acid, are... 

For example, if a polyester contains two acids and two diols each in equal concentrations of 0.25 moles, its [MI]ab is calculated from L=2, ma=mb=0.25. If the two acid units are terephthalic acid and iso-phthalic acid then they score [MI]a= 6 and 4 respectively and if the diol units are hydroquinone and methyl hydroqui-none, then these score [MI]b=6 and 5 respectively Eq. (2) becomes... 

The structure of an amorphous polyamide prepared from hexamethylenediamine and isophthalic/tere-phthalic acids was modified in order to determine the effect of chemical structure on the oxygen permeation properties. The greatest increase in permeation was obtained by lengthening the aliphatic chain. Placement of substituents on the polymer chain also led to increased permeation. Reversal of the amide linkage direction had no effect on the permeation properties. Free volume calculations and dielectric relaxation studies indicate that free volume is probably the dominant factor in determining the permeation properties of these polymers. 

Aldehyde benzoic acid, i.e., the half-aldehyde corresponding to phthalic acid, undergoes condensation with hydrazine to yield the hydrazone hydrazide (lactam-form). The lactim-form of this compound upon chlorination with phosphorus oxychloride gives the corresponding chloro derivative which on first treatment with a further mole of hydrazine and secondly with a calculated amount of hydrochloric acid affords the official compoimd. 

The charge vs. pH Curves 1 and 2 were calculated from alkalimetric titration curves of AUOs in the absence and presence of phthalic acid, respectively. The adsorption of total phthalic acid (formation of =AIXH and =AIX ) was determined analytically (Curve 3). Curve 4 was calculated from Curves 1 and 3 assuming that uncharged =AIXH only is formed. Curve 5 was calculated with the equilibrium constants given in Equation 24, the acidity constants of phthalic acid (—log Ko = 2.8, —log Kag = 4.9) (19). 

The first-order rate constant of the esterification of anhydrous phthalic acid catalyzed by nickel sulfates mounted on alumina and some other solid acids is shown in Table IV, together with the acidity of the catalysts measured by using p-dimethylaminoazobenezene as an indicator and the acidity calculated from the rate constants (cf. Section II). The catalytic activity correlates better with the acidity obtained by the latter method. The acidities measured by both methods coincide in the case of nickel sulfate, but do not in the case of silica-alumina. This is considered, according to Tarama et al., to be due to the fact that the Lewis acid sites which are assumed to be included in silica-alumina do not show catalytic activity. However, this might also be interpreted as due to the differences in acid strength and selectivity. 

Figure 2.27. Theoretical oxygen demand calculated for esters of phthalic acid and alcohols having different number of carhon atoms.

Kienle and Petke were among the first to study the effect on the ratio and properties of alkyd resin formation of acids other than phthalic acid or anhydride. In all cases where either aliphatic or aromatic acids were used the greatest time involved the first half of the reaction. The acid values near gelation were between the calculated values for the dimer and tetramer. The percent esterification attained at gelation was about the same for the different dibasic acids (approximately the same amount of water evolved). A summary of some other acids in comparison to phthalic anhydride is shown in Table V. 

The hydrolysis and alkylaminolysis products of phthalimide are phthalamic acid and A-substituted phthalamide, respectively, and these products show an insignificant absorption at 300 nm. The values of molar extinction coefficients of phthalamic acid and phthalic acids are same as 40 Af cm- at 300 nm. ° Thus, the calculated value of A for the reaction mixtures containing 0.50-M trimeth-ylamine at pH 10.95 (A 0.0, Table 7.2) is plausible in view of insignificant absorption of phthalamic acid at 300 mn. 

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